Naperville fire crews have yet to determine the cause of a midday blaze Thursday at the commercial warehouse of Odermath Inc. at 1651 Frontenac Road.

Fire units arrived on the scene and located a fire in a machine that had spread to a conveyor belt system and the building's ventilation system, Naperville Fire Chief Richard Mikel said in a release. Odermath specializes in molten metal treatment technology.

Though the fire in the original machine was brought under control quickly, a chemical material, Calcium metal, found in the ventilation system, complicated firefighting efforts because it is extremely reactive to water, the release said. Fire crews shut off the building's sprinkler system, which the fire had activated.

Firefighters worked for several hours to access the burning calcium metal residue. A truckload of road salt was brought in by the city's public works department to catch and extinguish the burning materials that were removed from the ventilation system, Mikel said.

No injuries were reported, though 12 employees were in the building at the time of the fire, Mikel said.

The Naperville Fire Department was assisted on the scene by Naperville police, Naperville Emergency Management Agency personnel, the Lisle-Woodridge Fire District, the Downers Grove Fire Department, the Aurora Fire Department, the Carol Stream Fire District, Naperville Public Works, and the DuPage County Office of Emergency Management and Homeland Security.